Meta-phenylenediamine, a useful chemical intermediate, has been prepared by the catalytic reduction of m-dinitrobenzene. Dinitration of benzene is difficult because the ring is deactivated and product separation is difficult, thus rendering the dinitrobenzene feedstock for m-phenylenediamine (M-PDA) synthesis very expensive. U.S. Pat. No. 4,387,247 discloses the reduction of di- or polynitro aromatic compounds by gaseous H.sub.2 S over a solid catalyst. CO gas is added to promote formation of amino groups from all nitro groups in the molecule. The disproportionation of toluenediamine (TDA) to m-PDA was reported as a secondary reaction under the CO/H.sub.2 S atmosphere.
U.S. Pat. No. 4,405,812 discloses a process for the ortho dealkylation of aromatic amines by contacting o-methyl substituted aromatic amines with a nickel catalyst at about 200.degree.-400.degree. C. The demethylation of dimethylanilines over nickel catalysts resulted in poor selectivity to the dealkylation product, toluidine when run under conditions similar to those used in aromatic hydrocarbon disproportionation.
U.S. Pat. No. 3,123,644 discloses a process for dealkylating a nuclear polyalkyl primary aromatic amine having a tertiary alkyl group of 4 or 5 carbon atoms on at least one ring carbon atom in the ortho-position with respect to the amino group. The polyalkyl primary aromatic amine is converted into a mono-nuclear aromatic amine by heating at a temperature in the range of 150.degree.-350.degree. C. under superatmospheric pressure with an acceptor aromatic amine and in the presence of a finely divided silica-alumina type catalyst.
U.K. patent application No. 810,751 discloses a process for the dealkylation of aromatic hydrocarbons. The process is carried out at a temperature from 450.degree. to 700.degree. C. and H.sub.2 pressure above 40 atmospheres in the presence of a catalyst comprising active carbon by itself or with a small amount of metallic activator.
The chemistry of carbon is not well defined in regard to role as a catalyst or catalyst support. Kirk, R. E., Encyclopedia of Chemical Technology. Vol. 2, pp. 881-899, discloses on page 885 that active carbon may be used as a catalyst in various reactions. In some instances it is used alone, for example, to catalyze the formation of sulfuryl chloride. However, more often it is used as a carrier for other catalysts.
For example, U.S. Pat. No. 4,331,557 discloses a process for regenerating ruthenium containing catalysts suitable for hydrogenation, dehydrogenation, isomerization disproportionation, and hydrocracking reactions. The reference states at col. 2, lines 16-29 that such ruthenium-containing catalysts may be supported on carbon, Kieselguhr, silica, alumina, silica-alumina, calcium carbonate, barium carbonate, pumice, clays and the like.